Generously season both sides of the beef with salt and fresh ground black pepper. Place a Dutch oven on high heat, and add the vegetable oil. When the oil is hot, brown the beef very well, about 5 minutes per side. It's important to get a nice brown crust on the meat. Remove the meat to a platter, and turn the heat down to medium.
Add the butter, diced onions, celery, and a pinch of salt. Saute for 4-5 minutes to brown slightly, then add the flour. Cook stirring for 2 minutes. Add the garlic, cook stirring for 1 minute. Whisk in the wine, scraping to deglaze the browned bits from the bottom of the pot. Add the tomato paste, and when the mixture begins to boil, pour in the chicken broth.
Add the bay leaf, thyme, and salt. When the liquid comes to a simmer, stir well, and place the beef back into the pot. Turn the heat down to very low, and simmer gently for about 45 minutes per pound, or until fork tender. After 2 hours, carefully turn the beef over, and continuing cooking until done.
While the pot roast is cooking, prepare the vegetables. Preheat oven to 425 degrees F. Add the potatoes, carrots, and parsnips to a shallow roasting pan. Skim a tablespoon of beef fat from the surface of the beef's braising liquid. Drizzle it over the vegetables, along with the melted butter. Toss the vegetables to coat, and season with salt and fresh ground black pepper. Roast in the oven for 20 minutes, or until the vegetables are almost tender. Remove and reserve.
About 5-10 minutes before the beef is done, uncover and add the vegetables to the pot. Continue cooking until the beef and vegetables just tender. Skim any remains pools of fat from the gravy. Taste and adjust for salt and pepper.